Pneumatic control system and pneumatic control device for such a system or the like

ABSTRACT

A pneumatic control system having a source of control fluid providing two different control pressure levels for respectively switching the control device of the system from one operating condition thereof to another operating condition thereof, the control device comprising a pair of condition controller means each having a sensor and a bleed-type pneumatic valve operated thereby together with relay means operatively interconnected to the source for directing a branch signal of the control fluid to a pneumatically operated device in relation to a pilot signal directed to a pilot chamber of the relay means by one of the control means. First and second passage means are adapted to respectively interconnect the source to the valves of the control means, a pressure responsive means being disposed in the first passage means for preventing fluid communication therethrough when the source is at one pressure level and permitting fluid communication therethrough when the source is at its other pressure level. A switching means is provided in a third passage means and has one position for interconnecting only the second passage means to the pilot chamber whereby the pilot signal for the relay means is provided only by one of the controller means and having another position for interconnecting only the first passage means to the pilot chamber whereby the pilot signal or relay means is provided only by the other controller means.

United States Patent Puster et a1.

[15 1 3,685,789 [451 Aug. 22, 1972 Inventors: Louis M. Puster; Edward M.Caldwell, both f Knoxville, Tenn.

Assignee: Robertshaw Controls Company,

Richmond, Va.

Filed: Sept. 21, 1970 Appl. No: 74,110

Related U.S. ApplicationData Division of Ser. No. 8l2,757, April 2,1969, Pat. No. 3,556,399.

[56] References Cited UNITED STATES PATENTS 7/1970 German ..25l/6l.1 X10/1951 McPherson ..251/61. 1 X 6/1962 Welch et al ..251/6l.1 X

Primary Examiner-Martin P. Schwadron Assistant ExaminerLeslie J. PayneAttorneyCandor, Candor & Tassone [57] ABSTRACT A pneumatic controlsystem having a source of control fluid providing two different controlpressure ,levels for respectively switching the control device of thesystem from one operating condition thereof to another Operatingcondition thereof, the control device comprising a pair Of conditioncontroller means each having a sensor and a bleed-type pneumatic valveoperated thereby together with relay means operatively interconnected tothe source for directing a branch signal of the control fluid to apneumatically Operated device in relation to a pilot signal directed toa pilot chamber of the relay means by one of the con trol means. Firstand second passage. means are adapted to respectively interconnect thesource to the valves of the control means, a pressure responsive meansbeing disposed in the first passage means for preventing fluidcommunication therethrongh when thesource is-at one pressure level andpermitting fluid communication therethrough when the source is at itsother pressure level, A switching means is provided in a third passagemeans and has one position for interconnecting only the second passagemeans to the pilot chamber whereby the pilot signal for the relay meansis provided only by one of the controller means and having anotherposition for interconnecting only the first passage means to the pilotchamber whereby the pilot signal or relay means is provided only by theother controller means.

3 Claims, 8 Drawing Figures PATENTEDwszzmn 4 3,685,789

SHEETlUF 3 PNEUMATIC CONTROL SYSTEM AND PNEUMATIC CONTROL DEVICE FORSUCH A SYSTEM OR THE LIKE This application is a divisional patentapplication of This invention relates to an improved pneumatic controlsystem as well as to an improved control device for such a pneumaticcontrol system or the like.

It is well known that pneumatic control systems have been providedwherein a pneumatic source has two different control pressure levels sothat the system will operate a pneumatically operated device in onemanner when the source is providing one of the control pressure levelsand will operate the control device in another manner when the pneumaticsource is providing the other control pressure level thereof.

For example, such control systems have been provided for controllingpneumatically operated heat exchanger devices of a building or the likewherein the one control pressure level is utilized to operate the 2pneumatically operated heat exchanger device for daytime operationthereof and, at nighttime, the control pressure of the pneumatic sourceis changed over to provide its other control pressure level foroperating the heat exchanger device for nighttime operation thereof.Also, such switching at different pressure levels has been utilized forswitching from heating operations of the heat exchanger means to coolingoperations thereof, such as a switching between winter and summeroperations.

It is a feature of this invention to provide a pneumatic control systemof the above v described type wherein two condition controller means areprovided for the system to respectively operate at the different controlpressure levels and each having a sensor and a bleed type pneumaticvalve operated thereby.

In particular, one embodiment of this invention provides a pneumaticcontrol system comprising a pair of condition controller means eachhaving a sensor and a bleed-type pneumatic valve operated thereby forrespectively directing a pneumatic pilot signal to a pilot chamber of arelay means which is operatively interconnected to the pneumatic sourcefor directing a branch signal of the control fluid to the pneumaticallyoperated device in relation to the particular pilot signal beingreceived in the pilot chamber thereof. First and second passage meansare respectively provided to be adapted to interconnect the source tothe valves of the controller means, a pressure responsive means beingdisposed in the first passage means for preventing fluid communicationtherethrough when the source is at one pressure level thereof andpermitting fluid communication therethrough when the source is atitsother pressure level. A third passage means is adapted to interconnectthe first passage means interrnediate the pressure responsive means andthe one controller means to the pilot chamber and is adapted tointerconnect the second passage means to the pilot chamber, a switchingmeans being disposed in the third passage means and having one positionfor interconnecting only the second passage means to the pilot chamberwhereby the pilot signal for the relay means is provided only by theother controller means and having another operating position forinterconnecting -.'only the first passage means to the pilot chamberwhereby the pilot signal for the relay means is provided only by the onecontroller means.

In one embodiment of this invention, a control device is provided andcomprises a housing means carrying the condition controller means, relaymeans, pressure responsive means andswitching means together with theinterconnecting fluid passage means so thatthe pneumatic control devicecan be remotely interconnected to the pneumatic source and to thepneumatically operated device for controlling the same in theabove-described manner.

Therefore, it is an object of this invention to provide an improvedpneumatic control system having one or more of the novel features setforth above or hereinafter shown or described.

Another object of this invention is to provide an im proved controldevice having one or more "of the novel features set forth above orhereinafter shown or described.

Other objects, uses and advantages of this invention are apparent from areading of this description which proceeds with reference to theaccompanying drawings forming a part thereof and wherein:

FIG. 1 is a front view of the improved control device of this inventionwith the cover plate thereof removed.

FIG. 2 is a schematic view, partially in cross section, illustrating theimproved pneumatic control system of this invention utilizing thecontrol device of FIG. 1.

FIG. 3 is an enlarged, exploded perspective view of certain of the partsof the control device of FIG. 1.

FIG. 4 is a fragmentary, enlarged side view of the control device ofFIG. 1 and illustrates the adjustment means for the condition controllermeans of the control device.

FIG. 5 is a view similar to FIG. 4 and illustrates the conditioncontroller means in another adjusted position thereof.

FIG. 6 is a view similar to FIG. 3 and illustrates another embodiment ofthe adjusting means for the condition controller means of the controldevice of this invention.

FIG. 7is a view similar to FIG. 4 and illustrates the embodiment of FIG.6 in one of its adjusted positions.

FIG. 8 isa fragmentary, cross-sectional view of the I reset means of thecontrol device of FIG. 1 and illustrates an improved porting arrangementfor the control device.

While the various features of this invention are hereinafter describedand illustrated as being particularly adapted to provide a pneumaticcontrol system for controlling a pneumatically operated heat exchangingdevice, it is to be understood that the various features 11, illustratedin fragmentary cross-sectional portions in FIG. 2 wherein the improvedcontrol system of this invention is generally indicated by the referencenumeral'12 and comprises a pneumatic control source ,13

adapted to selectively supply pneumatic pressure fluid v at twodifferentpressure levels; such as 16 p.s.i. and 25 p.s.i., and be interconnectedto an inlet passage means I 14 of the control device 10. The controldevice is adapted to have an outlet passage 15 thereof interconnected toa pneumatically operated device 16 of the system 12. The pneumaticallyoperated device 16 of the system 12 of this invention comprises apneumatically operated heat exchanging device which has its outputtemperature effect decreased upon an increase in pneumatic pressurefluid being directed thereto by the control device '10 of this inventionin, a manner hereinafter-described-and has its output temperature Ieffect increased upona decrease in the pneumatic pressure fluid beingdirected thereto by the control device 10 of this invention in a mannerhereinafter described.

, The housing 11 of the control device 10 as illustrated in FIG.2car'ries a pair .of condition control means 4 I shaft 56 adapted to beinterconnected to a control knob (not shown) wherein the'operator canadjust the.

cam 55 relative to the control device 10 in relation to a temperaturescale 157, FIG. 1, to set the temperature 1 that control system 12 is tomaintain in the manner hereinafter described. 7 1

The tension spring 50 of the pivot plate 41 is so located relative tothe three pivots 42, 43 and 53 of the plate 41 that the same is disposedwithin the triangle defined by the three pivots 42, 43 and-53 topositively maintain the plate pivot 53 against the cam surface 54 of thecam 55 in all of the operating positions of the cam 55, the hole 48 forthe pivot pin 43 defining a center of rotation for the plate and theV-shaped' notch 49 for the pivotpin' 42 preventing such rotationwhereby'the pivot plate assembly .41 .ispositively located onthehousing'me'aris- 1-1 of the control device v10. In this manner,rotation of the cam 55 will cause the respectively andgenerallyindicated by. the. reference tively sensing the output temperatureeffect of the heatexchanger means .16 and respectively being carried incantilevered fashion by. levers or blade means and 26, FIGS. 1 and 3,mounted to the housing means 11 of the control device 10. i

. In particular, the lever or blade means 25 and 26 respectively haveadjacent ends 27 and 28 interconnected to leaf springs 29 and 30 attheends 31 and 32 thereof 1 with the leaf springs 29 and 30 respectivelyhaving the other ends 33 and 34 thereof fixed to the housing means 11 ofthe control device 10 by fastening means 35 and 36*as illustratedin-FIGS. 1 and 4 so that the free ends 37 and 38 of the blades 25 and 26are normally urged downwardly by the leaf springs 31 and 32 in FIG. 4whereby adjusting screws or threaded members 39 and 40 respectivelycarried by the free ends 37 and38of the blades25 and 26 will bearagainst a movable wobble or pivot plate 41 of the control device 10.

The pivot or wobble plate 41 carries a pair of downwardly extending pins42 and 43 disposed along a line 44 of the plate 41 that is parallel to aline 45 on the plate 41 that passes through the respective points 46 and47 of engagement of the threaded adjusting members 39 and 40 of theblades 25 and 26 as illustrated in pin 42 or 43, a tension spring 50having one end 51 attached to the plate 41 and the other end '52 thereofattached to the housing means 11 pulls the plate 41 downwardly at alltimes toward the housing 1 1 whereby a forwardrounded pin 53 of thepivot plate 41 bears against a cam surface 54' of a cam member 55rotatably mounted to the housing means 11 and having a control plate41to pivot about the pivot line44 in the manner illustrated in FIGS. 4 and5 to adjust the location of the free ends 37 and 38 of the levers orblades 25 and 26 relative'to the housing means 11 and, thus, theposition of the bimetal members 23 and-24 relative to the bleedvalves 19and-20 whereby the c0ntr0l ;setting of the condition controller means 17and 18 can be adjusted for apurpose hereinafter described; v

The levers orblades 25 and '26 respectively have.

rectangular openings 57 and 58 passing therethrough intermediate theopposed ends thereof and the bimetal members 23 and 24 respectively havethe ends 59 and. ,60 thereof secured to the blades 25 and 26 in such amanner that the free ends 61 and 62 of the bimetal members 23 and 24 areexposed at the cutouts 57 and 58 and are located over the valves. 19 and20 of the bimetal members-23 and 24 relative to the valves 19 and 20 orthe condition controller means 17 and 18 can be adjusted by the cam 55whereby movement of the cam 55 adjusts the free ends 61 and 62 ofthebirnetal members 23 and 24 relative to the respective valves 19 and20 in the same direction'toward 7 However, by merely locating the pivotpins 42 and 43 of the pivot plate 41 in different locations fromthat'illustrated in FIG. 3, the same pivot plate 41 can be utilized toadjust one of the bimetal members 23 or 24 inone direction relative toits respective valve and the. other bimetal member 24 or 23 will beadjusted in the I opposite direction relative to its respective valve.

For example, this other arrangement is illustrated in FIGS. 6 and 7 andthe parts of the control device 10A illustrated in FIGS. 6 and 7 thatareidentical to the parts of the control device 10 previously described areindicated by like reference numerals followed by the reference letter A.

As illustrated in FIGS. 6 and .7, the pivot'pins 42A and-43A are mountedalong a line 63-on the plate 41A 1 located V shaped notch 64 andcone-shaped hole 65 1 formed in the housing means 11A in a mannersimilar to the notch 49 and cone-shaped hole 48 of the control device topositively locate the plate 41A to the housing means 11A of the controldevice 10. The forward pivot pin 53A of the plate 41A bears against thecam surface 54A of the rotatable cam 55A and the tension spring 50A isstill located within the triangle defined by the pivot pins 42A, 43A and53A to maintain the pivot plate 41A'against the housing means 1 1A.

In this manner, when the cam 55A is rotated relative to the housingmeans 11A for adjustment thereof, the resulting action on the pivotplate 41A is such that one of the bimetal members 23A or 24A will bemoved in one direction relative to its particular valve 19A or A and theother bimetal member 24A or 23A will be moved relative to its respectivevalve 20A or 19A in the opposite direction because the plate 41A willpivot about the pivot line 63 illustrated in FIG. 6.

Thus, it can be seen that the arrangement of the control device 10 ofthis invention can utilize the, same parts only slightly modified in thepivot pin locationof the plate 41 thereof to provide a device which willeither adjust both of the bimetal sensors 23 and 24 in the samedirection upon an adjustment of the cam 55 thereof or provide adjustmentof the bimetal members. 23A and 24A in the opposite directions thereofupon rotation of the cam 55A so that the improved features of thisinvention readily permit the control device of this invention to provideday-night switching'wherein both bimetal members 23 and 24 are directacting as will be apparent hereinafter or the control device 10A can beprovided for summer-winter switching wherein one of the blades 23A or24A will be direct acting and the other bimetal member 24A or 23A willbe reverse acting.

For example, in the control system 12 illustrated in FIG. 2, bothbimetal blades 23 and 24 move or warp toward their respective valves 19and 20 upon an increase in sensed temperature and move or warp away fromtheir respective valves 19 and 20 upon a decrease in sensed temperature.

In the control device 10A, the blade 24A moves or source 13 at the inlet14 of the housing means 1 l and to the outlet opening 21 of the valve19. However; a pressure responsive means 67 is provided in the housingmeans 11 of the control device 10 in the first passage means 66 and isdefined by an inlet 68 and anoutlet 69 separated by a valve seat 70 ofthe housing 11 with the inlet 68 being interconnected to the part71 ofthe first passage means 66 that leads from the source 13 and with theoutlet 69 being interconnected to the part 72 of the first passage means66 that leads to the opening 21 of the valve 19.

- The pressure responsive means 67 includes a flexible diaphragm 73 heldbetween housing parts 74 and 75 to cooperate therewith and define achamber'76 adjacent one side 77 of the diaphragm 73 and interconnectedto the inlet 68 andadapted to be'interconnected to the warps toward itsrespective valve 20A upon sensing a outlet 69 when the valve seat 70 isopened. The other side 78 of the flexible diaphragm 73 cooperates withthe housing means 11 to define anotherchamber 79- to be manuallydepressed in a manner hereinafter described. A compression spring 86 isdisposed in the chamber 79 and has one end 87 bearing against thefitting 81 and the other end 88 thereof bearing against the enlarged end84 of the reset member 83 so as to tend to maintain theend 84 againstthe side 78 of the diaphragm 73 whereby the reset member 83 will followmovement of the diaphragm member 73.

The force of the compression spring 86 is such that the same willmaintain the flexible diaphragm 73 against the valve seat 70 so as toprevent fluid communication through the first passage means 66 when thepressure source 13 is providing a control pressure at the lower of itstwo levels, such as 16 p.s.i. so that when the pressure source 13 is atits lowest control level, the pressure source 13 is not interconnectedto the outlet 21 of the valve 19 of the condition controller means 17since the spring 86 maintains the diaphragm 73 closed against the valveseat 70. However, when the pressure heat exchanger device that is to becontrolled by the summer-winter control device 10A of this invention hasits air-conditioning operation controlled by the bimetal member 24A andits heating operation con-.

source 13 is set to provide the higher of its two control pressurelevels, such as 25 p.s.i., the force of the higher pressure level in thechamber 76 of the pressure responsive means 67 exceeds the force of thecompression spring 86 so as to move the diaphragm 73 upwardly andthereby open the valve seat so that the pressure source 13 at its higherpressure level is fluidly interconnected to the outlet 21 of the valve19 of the condition controller means 17. In this manner, it can be seenthat the pressure responsive means 67 permits fluid communicationthrough the first passage means 66 when the pressure source 13 isproviding its higher pressure control level and prevents fluidcommunication through the passage means 66 when the pressure source 13is providing its lower control pressure level.

The housing means 11 has a second passage means 89 provided thereinwhich is adapted to interconnect the outlet 22 of the valve means 20 ofthe condition v controller means 18 to the source 13, the second passagemeans 89 being illustrated in FIG. 2 as having a branch passage means 90fluidly interconnected to the first passage 66 intermediate the source13 andthe pressure responsive means 67. A normally open pressureresponsive valve means 91 is disposed in the passage means 89intermediate the valve 20 of the condition controller means 18 and-thesource 13, the nor- 'mally open pressure-operated valve' means 91 havinga pneumatic actuator'92 therefor interconnected by a passage means 93 tothe outlet 69 of the pressure responsive means 67 so that when thepressure respon-' sive means 67 is moved to its open position by thepneumatic source 13 providing the higher control pressure level thereof,suchsource 13 is also interconnected to the actuator 92 of the normallyopen pressure-operated valve means 91 to close the same and therebyprevent ,fluid communication through the second passage means89 to thevalve 20 of the conditioncontroller means 18. j i. j s f fA restrictor94 :is disposed in the second: passage .89 intermediate the pressureoperated valve I 91 and-the source 13'.

The housing means .11 of the control device is provided with apneumatically operated switching means'95 therein which,- as illustratedin FIG. 2, comt a pair of inlets'96 and,97 respectively formed in' 'the'housing means lland being separated from each other by a pair of opposedvalve seats 98 and 99 formed 'in the housing means 11 and adapted to beopened and closed by a movable valve member 100 being carried by aflexible diaphragm 101 that cooperates with the housing means 11 todefine two chambers 102 and 103 on opposed sides thereof, The chamber102 is interconnected to the inlet 97 and is adapted to be fluidlyinterconnected ,to another chamber 104' formed in the housing means 11when the valve seat 99 isopened, the inlet 96'alsobeing adapted to beinterconnected to the chamber 104 when the valveseat 98 is opened. Thepart 72 of the first passage means 66 is fluidly interconnected to apassage 105 formed in the housing means 11' and ,disposed in fluidcommunication with the chamber 103, the part 72 of the first passage 66inter- I mediate the passage 105 and the valve 19 of the conditioncontroller means 17 also being interconnected to the chamber 102 by apassage means 106 that leads to inlet 97'. A restrictor 107 is disposedin the part 72 of the first passage means 66 intermediate the passage,means 105 and 106 as illustrated in FIG. 2.

The inlet 96 of the switching device 95 is interconnected to the secondpassage means '89 by a branch passage means 108 that is disposedintermediate the normally opened pressure-operated valve means 91 andthe valve 20 of the controllermeans l8.

The chamber 104 of the switching device 95 is interconnected by apassage means 109 in the housing means 11 of the control device 10 to apilot pressure chamber 110 of a pneumatic relay'portion l'll of thecontrol device l0.

' As illustrated in FIG. 2, the pneumatic relay 111 has a pair ofchambers 112 and 113 formed in the housing means 11 and being separatedby a stationary valve seat 114 adapted to be opened and closed by avalve member 115 normally urged to its closed position by a compressionspring 116disposed in the chamber 112. The chamber 112 is adapted to beinterconnected to the inlet 14 of the control device 10 by a passagemeans 117 formed in the housing means 11so as to alwaysbe in fluidcommunication with the source 13 whereby the chamber 1 12 is themainpressure chamber of the relay- 3 111. The chamber 113 isinterconnected by a passage means 1 18 formed in the housing means 1 1to the inlet of the pneumatically operated heat exchanger device 16whereby the chamber 113 is a branch pressure chamber of the relay 111and supplies the varying pressure to the pneumatically operated device16jto control the same in relation to the pilot signal being received inthe pilot charnber 110 of the relay 111 by the .controller means 17 or18 in the manner hereinafter described.

The inlet 15 of the pneumatically operated device 16 .is alsointerconnected to the second passage means 89 by. a passage. means 119formed in thehousing means 1 1 and having a res'trictor 120 therein.

"The. pneumatic relay 1l1'has 'a movable valve seat member 121 carriedby two flexible vdiaphra grns 122 and l23which are 'se cured in thehousin g means 11 in v sucha manner that the same define a chamber 124therebe tween which is interconnected to .the at mosphere by a passagemeans 125 formed in the housing means .11 whereby the chamber 124 is anexhaust chamber for the relay. 111. The diaphragm 122 cooperates withthe housing means "11 to define the pilot pressure chamber and thediaphragm 123 cooperates with thehousing means 11 branch pressurechamber 113.

The valve member 121 of the relay lllhas an open-' ing 126 passingtherethrough and interconnecting the exhaust chamber 124 to the branchpressure chamber 113 ata valve seat 127 of the valve member 121.However, the valve member has an. extension 1285 adapted to pass throughthestationary valve seat 114 and be engageable with the valve seat 127of member 121 to closethe valve seat 127 and thereby prevent fluidcommunication between the branch pressure chamber 113 and the exhaustchamber 124.

From the above description of applicants improved pneumatic controlsystem 12 and the control device 10 .of this invention, it can be seenthat the control device 1 10 is adapted tocontain all of the systemparts illustrated in FIG. 2 except for the pneumatically operated heatexchanger device 16 and the pneumatic source 13.

However, it is to be understood that in order to practice the pneumaticcontrol system of this invention, the

ing part having a cavity therein also facing .the-

diaphragm in aligned relation with the first-named cavity, a passageisrun to the cavity parallel to the surface of that housing part whichengages the and then a cross drilling is provided through the otherhousing part, flexible diaphragm and thefcavity containing housing partto fluidly interconnect to the passage that was formed in the housingpart intermediate its upper and lower'surfaces. Such an arrangement isprovided by the inlet passage 97 to cavity 102 of the switching todefine the means 95, illustrated in FIG. 2. This permitted the diaphragmcavity to be completely sealed around its periphery by the flexiblediaphragm being sandwiched between the facing surfaces of the twohousing parts. Thiswas necessary because the air passage to theparticular cavity must not be run directly into the cavity through thediaphragm as this would leave a leakage path on the other side of thediaphragm above the passage from the point that the same enters into thecavity through the diaphragm to the diaphragm cavity.

One feature of the control device 10 completely eliminates the need forthe above described cross drilling operation.

For example, reference is now made to FIG. 8 wherein the housing means11 includes the two housing parts 74 and 75 respectively having thefacing surfaces 130 and 131 thereof secured together with the previouslydescribed flexible diaphragm 73 disposed therebetween and cooperatingwith adjacent cavities 138 and 129 in the housing parts 74 and 75 todefine the previously described chambers 76 and 79. The face 131 of thehousing part 75 is interrupted by a cylindrical closed end bore 132which is interconnected to the chamber 76 by a slot or groove 133 alsointerrupting the face 131 of the housing part 75 throughout the spacingbetween the bore 132 and the chamber 76.

The diaphragm 73 is provided with a small opening 134 in alignedrelation with the bore 132 in the housing part 75. The housing part 74has an integral tubular extension 135 extending from the face 130thereof in aligned relation with the bore 132 of the housing part 75 andwith a diameter larger than the normal diameter of the opening 134 inthe diaphragm 73 so that when the housing parts 74 and 75 are assembledtogether with the flexible diaphragm 73 therebetween, the tubularextension 135 of the housing part 74 is forced through the opening 134in the diaphragm 73 to project into the bore 132 so that the stretchedopening 134 of the diaphragm 73 provides an annular lip 136 of thediaphragm 73 completely about the tubular extension 135 to completelyseal the same from the face 130 of the housing part 74. A passage 137 isformed completely through the housing part 74 and tubular extension 135thereof as illustrated in FIG. 8 so that to fluidly interconnect theexterior of the housing part 74 with the bore 132 of the housing part 75and, thus, to the chamber 76 by the interconnecting slot or groove 133.

This porting method of this invention of allowing the channel or passageto be run directly to the diaphragm cavity and eliminating any leakageabove the channel, eliminates the expensive cross-drilling operation.Further, the closeness of fit between the tubular extension 135 and thebore 132 in the housing part 75 makes against bending and warping withthe leak port leve'rassemblies 25 and 26 being made in channel shape toprovide stiffness together with heavy flexure springs 29 and 30 tosuspend such blade means 25 and 26 so that the control device 10 ishighly accurate and operates in a manner now to be described.

Assuming that the lower pressure level of the pneumatic source 13, suchas 16 p.s.i., is to be utilized by the control system 12 for controllingthe pneumatically operated heat exchanger means 16 during the daytimeoperation wherein the condition controller means 18 will supply thepilot signal to the relay means llland that the higher pressure level ofthe pneumatic source 13, such as 25 p.s.i., will be utilized to ope'ratethe heat exchanger means 16 during the nighttime operation of the system12 wherein the condition controller means 17 will supply the pneumaticsignal for the relay 111, and assuming that the operator, has set thecam member of the control device 10 in a desired set point positionthereof wherein the previously calibrated adjusting means 39 and 40 ofthe blade means 25 and 26 will provide a set point temperature of 70that the heat exchanger means is to maintain during the daytime and atemperature of during the nighttime, the operation of the control system12 during the daytime operation is as follows.

With the pneumatic pressure source 13 providing its lower outputpressure level, such as 16 p.s.i., the spring 86 of the pressureresponsive means 67 of the control device 10 maintains the diaphragm 73against the valve seat so that no fluid pressure is supplied through thefirst passage means 66 of the control device 10 to the valve 19 of thecondition controller means 17. However, when such valve seat 70 of thepressure responsive means 67 is closed, no pressurefluid is beingsupplied to the actuator 92 of the normally opened valve means 91 sothat the valve means 91 is in its open position. Similarly, no pressurefluid is supplied to the chamber 103 of the switching device 95 sincethe switching device is maintained in its normally closed position underthe urging of spring 95. Therefore,it can be seen that the low pressurelevel of the source 13 is free to pass through the second passage means89 to the outlet 22 of the valve 20 of the condition controller means 18as well, as through the branch passage 108 A and into the chamber 104 ofthe switching means 95 it possible to fit the extension 135 through thesmall I since switching means 95 is maintained in its nonnally closedposition under the urging of spring 95' holding valve member againstvalve seat 99 preventing entrance of pressure fluid into cavity 102.With the valve member 100 of the switching device 95 closing the valveseat 99, it can be seen that the passage 89 of the control device 10 isalso interconnected intermediate the restrictor 94 and the outlet 22 ofthe valve 20 of the condition controller means 18 to the pilot chamber 110 ofthe relay 111.

With the birnetal member 24 of the condition controller means 18 sensingthe selected output temperature effect for the heat exchanger means 16,the bimetal member 24 is so positioned relative to the opening 22 of thevalve of the condition controller means 18 that the pilot pressuresignal being delivered by the switching device 95, in the positionillustrated in FIG. 2, to the pilot chamber of the relay 111 is suchthat the relay 111 has the pressure in the branch chamber 113 thereofthat is supplied to the pneumatically operated heat exchanger means 16at a pressure level that maintains the heat exchanger means 16 at a,

branch chamber 113 is also out of fluid communication with the exhaustchamber 124 whereby thesystem remains in the condition illustrated inFIG. 2..

However, should the, output temperature effect of the heat exchangermeans 16 rises above the selected temperature setting of the cam 55 forthe daytime operation, the bimetal member 24 warps or moves closer tothe opening'22 of the valve 20 of the condition controller means 18whereby the pneumatic signal being delivered to the pilot chamber 110 bythe controller'means 18 increases in pressure value so as to move thevalve member 121 downwardly and carry the valve member 115 therewith inopposition to the force of the compression spring 116 to open the valveseat 114 and, thereby, introduce an increased pressure in thebranch'pressure chamber 113. The increasedpressure in the branch chamber113 is conveyed to the pneumatically operated heat exchanger 16 to causethe same to decrease its output temperature eflect proportional to theincrease in the pneumatic pilot signal being directed to the chamber 110by the controller means I8. When the decreased output of the heatexchanger means 16 brings the temperature adjacent thebimetal member 24back up to the selected temperature setting of the device 10, the relaymeans 111 returns to the position illustrated in FIG. 2. Conversely,should the output temperature efl'ect of the heat exchanger means 16 assensed by the bimetal member 24 fall below the selected temperatureeflect, the decreased temperature being sensed by the bimetal device 10is subsequently reached by the heat exchanger means 16, the bimetalmember 24 moves back toward the valve member 20 of the controller means18 to return the relay means 111 to the position illustrated in FIG. 2.

Therefore, it can be seen that the controller means 18, by varying theposition of the bimetal member 24 relative to the valve 20 thereof, isadapted to maintain a selected output temperature effect for the heatexchanger means 16 throughout the entire time that the pneumaticpressure source 13 is providing the control pressure at its lowerpressure level.

When it is desired to switch the system 12 over to its nighttimeoperation, either by a manual change in the setting of the outputpressure level of the source 13 or by automatic timed switchingoperafion, the change in the output pressure level of the source 13 tothe higher pressure level, such as 25 p.s.i., causes the system 12toswitch over to its nighttime operation so that the heat exchangermeans 16 will be controlled by the nighttime condition controller means17. 1

In particular, when the pressure being directed into the part 71 of thepassage means 66 is at the higher pressure level of the source 13, suchincreased pressure in thechamber 76 of the pressure responsive means 67overcomes the force of the compression spring 86, which is set to beovercome by a pressure of about 20 p.s.i. when the two pressure levelsbeing considered are 16 p.s.i. and 25 p.s.i. as previously described,whereby the diaphragm 73 moves away from the valve seat 70 so as tointerconnect the pressure source 13 to the part 72 of the first passagemeans 66 and, thus, to the valve 19 of the pressure control means 17Simultaneously, the opening of the valve seat 70 directs fluid pressureto the actuator 92 of the normally opened pneumatically v operated valvemeans to causethe same to close and member 24 causes the same to warpaway from the to open the valve seat 127 away from the valve extension128 of the valve member 115- so that the branch chamber 113 isinterconnected to the atmosphere through the exhaust chamber124.-Accordingly, the pressure in the branch chamber 113 decreases sothat the pressure to the pneumatically operated heatexchanger 16 alsodecreases whereby the heat exchanger means 16 increases its heatingoutput proportionately to the decrease in the pneumatic pilot signalbeing directed to the chamber 110 at the relay 111 by the controllermeans 18. Thus, when the selected temperature effect setting of thecontrol thereby disconnect the condition controller means 18 from thesource 13. Since the pressure source must pass through the restrictor107 in the part 72 of the first passage means 66 before the same reachesthe branch passage 106 disposed intemiediate the restrictor 107 and thevalve 19 of the condition controller means 17,

a greater pressure is provided by the branch passage 105 into thechamber 103 of the switching means 95 than into the chamber 102 asprovided by the branch passage 106 so that the resulting pressuredifferential across the diaphragm 101 causes the diaphragm 101 to movedownwardly and overcome the force of spring 95 and thereby move thevalve member away from the valve seat 99 and into engagement with thevalve seat 98 to disconnect the chamber 104 from the outlet 22 of thevalve 20 of the condition controller means18.

With the valve seat 99'now opened, it can be seen that the chamber 104of the switching device 95 is now interconnected tothe valve 19 of thecontroller means 17 so that the pilot signal being directed by thepassage 109 into the pilot chamber 110 of the relay 111 is under theinfluence of the controller means 17 whereby the controller means 17operates the pneumatically operated heat exchanger means 16 in the samemanner as the controller means 18 previously described. Thus, suchoperation need not be further described except to state that thecondition controller means 17 operates the output temperature effect ofthe heat exchanger means 16. to tend to maintain the same at theparticular temperature setting level as has been previously selected bythe cam member 55 for nighttime'operation.

The restrictor 120 in the passage 119 that interconnects the pneumaticsource 13 to the branch pressure chamber 113 of the relay 111 isprovided to bleed the pneumatic pressure source 13 to the branchpressure chamber 113 to initially keep the relay 111 balanced with thevalve member 121 against the valve part 128 so as to prevent oreliminate a hysteresis effect.

Therefore, it can be seen that the improved control system 12 andcontrol device of this invention are so constructed and arranged thatthe control device 10 is adapted to automatically switch the operationof the pneumatically operated device 16 between the controller means 17and 18 depending upon the change in pressure level of the pneumaticsource 13.

For example, with the control system 12 previously 4 operating under thehigher pressure level of the pneumatic source 1 3, a subsequent changein the output pressure level of the source 13 from its higher pressurelevel to its lower pressure level causes the flexible diaphragm 73 ofthe pressure responsive means 67 to close against valve seat 70 andthereby terminate the flow of fluid through the-first passage means 66to the controller means 17 whereby the previously closed valve means 91will open to interconnect the source 13 to the valve of the conditioncontroller means 18.

With the loss of pressure in the chamber 103 of the switching means 95by the closing of the diaphragm 73 same procedure with the controllermeans 17 at the illustrated in FIGS. 6 and 7 wherein only the pivot pinlocation on the adjustable pivot plate 41A has been changed from the pinlocation of the plate 41, it can be seen that such modified controldevice will operate in the same manner as the control device 10 for thesystem 12 of FIG. 2 previously described except that at the higherpressure changeover of the source 13, the controller means 17 will beoperated to control the heat exchanger means 16-at either the summeroperation or winter operation thereof with the bimetal member 23 of thecontrol means 17 being direct acting, that is movable away from thevalve 19 of the controller means 17 upon sensing a decrease intemperature while the bimetal member 24 is moving toward the valve 20 ofthe controller means 18 upon the sensing of the decrease in temperature.

Thus, it can be seen that the control device 10 of this operation in anautomatic manner wherein the various against the valve seat 70 of thepressure responsive means 67, the pressure in chamber 103 beingexhausted through controller means 17 allows switching means 95 toreturn to its normally closed position under the urging of spring 95' sothat the system 12 is now completely switched over to the lower pressuresetting thereof whereby the controller means 18 will operate the heatexchanger device 16 in the manner previously described.

The manually operated reset means 83 of the pressure responsive means 87of the system 12 is so constructed and arranged that the end 85 thereofprotrudes from the housing means 11 when the diaphragm 73 is movedupwardly because the pressure source 13 is providing its higher pressurecontrol level.

This feature makes it possible to check the calibration on both leakport means of the controller means 17 and 18 of the control device 10 orto recalibrate either in a building or the like with only the use of thehigher pressure output level of the source 13 because the operator canpush downwardly on the protruding portion 85 of the reset member 83 tomanually close the diaphragm 73'against the valve seat 70 so that at thehigher pressure level, the system 12 will be switched over from thecontroller means 17 to the controller means 18 for such checking orcalibration operation. This eliminates the need for the operator havingto switch the pressure level of the source 13 back to its lower pressurelevel to go through an entire building to check the calibration of thecontroller means 18 for each control device 10 after having gone throughthe parts of the control device 10 of this invention operate in anunique manner to control the system 12 in an efficient and economicalmanner.

Accordingly, it can be seen that not only does this invention provide.an improved pneumatic control system, but also this invention providesan improved control means for such a system or the like.

What is claimed is: A

1. In combination, a pair of housing parts having adjacent faces securedtogether, and a flexible diaphragm disposed between said adjacent facesto seal the same from each other, one of said parts having a cavityinterrupting said face thereof and being disposed adjacent saiddiaphragm, said diaphragm having an opening passing therethrough alignedwith said cavity, the other ing from the exterior thereof through saidextension to thereby interconnect the exterior of said other housingpart to said cavity.

2. A combination as set forth in claim 1 wherein said one housing parthas another cavity interrupting said face thereof in spaced relation tosaid first-named cavity, said diaphragm sealing said other cavity fromsaid face of said other housing part, and passage means fluidlyinterconnecting said cavities together.

3. A combination as set forth in claim 2 wherein said passage means isprovided in said one housing part and interrupts said face thereof fromsaid first-named cavity to said other cavity.

1. In combination, a pair of housing parts having adjacent faces securedtogether, and a flexible diaphragm disposed between said adjacent facesto seal the same from each other, one of said parts having a cavityinterrupting said face thereof and being disposed adjacent saiddiaphragm, said diaphragm having an opening passing therethrough alignedwith said cavity, the other housing part having a tubular extensionprojecting from the face thereof and passing in a press-fit mannerthrough said opening in said diaphragm and into said cavity and therebyhaving its exterior sealed by said diaphragm so that no leakage of fluidcan take place between said tubular extension and said diaphragm andthereby enter the area between said diaphragm and said adjacent face ofsaid other housing part even though said cavity is disposed outboard ofsaid adjacent face of said other housing part adjacent said tubularextension thereof, said other part having a passage leading from theexterior thereof through said extension to thereby interconnect theexterior of said other housing part to said cavity.
 2. A combination asset forth in claim 1 wherein said one housing part has another cavityinterrupting said face thereof in spaced relation to said first-namedcavity, said diaphragm sealing said other cavity from said face of saidother housing part, and passage means fluidly interconnecting saidcavities together.
 3. A combination as set forth in claim 2 wherein saidpassage means is provided in said one housing part and interrupts saidface thereof from said first-named cavity to said other cavity.